Question 1

How to use promises in Concurrent Ruby for async tasks?

Accepted Answer

Use the Promises framework with `Concurrent::Promises.future` to execute code asynchronously; it supports chaining with `.then` and error handling via `.rescue`, providing a non-blocking, lock-free implementation as described in the documentation.

Question 2

Concurrent Ruby vs Sidekiq for background jobs – which is better?

Accepted Answer

Concurrent Ruby is a library for building custom concurrency patterns within your app, ideal for fine-grained control over threads and state. Sidekiq is a full job processing system with Redis-backed queues; choose Concurrent Ruby for internal concurrency, Sidekiq for managed job processing.

Question 3

Is Concurrent Ruby thread-safe on MRI Ruby?

Accepted Answer

Yes, it's designed for thread safety across all major Ruby interpreters, including MRI, through synchronized data structures and concurrency abstractions. However, developers must still avoid sharing mutable objects incorrectly, as noted in the thread safety section.

Question 4

How to install Concurrent Ruby with C extensions?

Accepted Answer

Add both `gem 'concurrent-ruby'` and `gem 'concurrent-ruby-ext'` to your Gemfile, then run `bundle install`. The core gem auto-detects extensions for performance boosts on MRI, but this adds installation complexity in constrained environments.

Question 5

What are actors in Concurrent Ruby and are they stable?

Accepted Answer

Actors implement the Actor Model for message-passing concurrency, available in the edge gem. They're experimental with partial documentation and tests, so APIs may change; use with caution in production systems.

Question 6

How to handle errors in Concurrent Ruby promises?

Accepted Answer

Errors are managed using `.rescue` to catch exceptions in promise chains, ensuring failures propagate gracefully. The Promises framework includes built-in error handling, but developers need to explicitly design for fault tolerance.

Concurrent Ruby

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